Techniques for reducing a leakage current from a load have hitherto been proposed. For example, Japanese Patent No. 3044650 and Japanese Patent Application Laid-Open No. 11-122910 (1999) to be described below disclose techniques such that a compensating current supply circuit connected across a smoothing capacitor outputs a current which compensates for a leakage current from a load.
In a structure provided with no smoothing capacitor in Japanese Patent Application Laid-Open No. 2000-92861, a noise reduction circuit is provided between positive and negative input lines providing a connection between a diode bridge serving as a full-wave rectifier circuit and an inverter device. The noise reduction circuit has two transistors which perform the operation of turning on and off so as to be in states opposite to each other.